The pharmacy posts a sign, your doctor's office sends a reminder, and the same quiet question comes back. Does the flu shot really do anything this year?
A systematic review published in JAMA on September 2, 2026 pulled together 69 studies on the 2026-2027 flu vaccine.
The short answer is yes. The protection is strongest against the most serious outcomes, and it varies by age.
The review was led by researchers at the Evidence Foundation and McGill University. It drew on randomized trials, observational studies, product safety data and disease burden reports covering flu seasons from 2015 through 2026.
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Protection against hospitalization by age
Keeping people out of the hospital is the outcome the shot handles best. The review's numbers for the latest seasons look like this.
Age group | Vaccine effectiveness against hospitalization |
|---|---|
6 months to 17 years | 53% (95% CI 47-59) |
18 to 64 | 29% (95% CI 11-45) |
65 and older Also read: Smoked fish recalled over listeria fears: Check your fridge now | 19% in men to 43% in women |
In children and teenagers, vaccination was linked to an 80 percent lower risk of dying from a flu-related illness.
In older adults, the newer adjuvanted vaccine, a formulation designed to produce a stronger immune response, was tied to a roughly 66 percent lower risk of flu-related death.
Ordinary doctor visits
Protection against showing up at the doctor's office with lab-confirmed flu is lower than protection against being hospitalized.
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For the 2025-2026 season, the review reported outpatient effectiveness of about 41 percent in adults 65 and older. In adults 18 to 64 the figure was around 24 percent.
In practice, the shot blunts the course of flu more than it stops every mild case. You can still catch the virus and feel rough for a few days, but your odds of ending up in a hospital bed go down.
No new safety concerns in a 9.9 million person review
Safety looked reassuring. A large study of 9.9 million people found no increased risk of serious side effects. That included Guillain-Barré syndrome, a rare condition where the immune system attacks the nerves.
The same reassuring picture held when the flu shot was given alone and when it was given at the same visit as a COVID-19 or RSV vaccine.
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For pregnancy, the review found a vaccine effectiveness of 44 percent against flu infection in infants under 6 months old, when the mother was vaccinated in any trimester.
When to get it this year
The CDC says most people should ideally be vaccinated by the end of October.
September and October are the recommended window because the body needs about two weeks to build full protection. Flu activity usually climbs through November and peaks between December and February.
Children who need two doses are the exception and can be vaccinated earlier.
Older adults and women in the first or second trimester of pregnancy are told not to get the shot in July or August, because the protection can fade before the peak.
Even late October still falls inside the CDC window, and vaccination continues to be offered throughout the season as long as flu viruses are circulating.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.